AD 96-23-19

Events Leading to the Issuance of This AD The FAA has received reports involving Air Tractor Models AT-402 and AT-502 airplanes, where the flap actuator overtravel stop nut disengaged from the jack screw. The flap pushrod pressed against the aileron pushrod, which caused difficulty in moving the ailerons. Snow Engineering Co. (the parent company of Air Tractor) and the FAA have simulated this condition on factory airplanes through a laboratory environment, which resulted in the same difficulty in moving the ailerons.

This condition, if not detected and corrected, could result in loss of aileron control on certain Air Tractor Models AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-401A, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-502B, and AT-503A airplanes.

Applicable Service Information Snow Engineering Co. has issued Service Letter (SL) #140, dated November 27, 1995, Revised October 10, 1996, which applies to certainAir Tractor AT-300, AT-400, and AT-500 series airplanes. This SL specifies procedures for installing both a new flap actuator overtravel stop nut and a roll pin through the overtravel stop and jack screw.

The FAA's Determination After examining the circumstances and reviewing all available information related to the incidents described above, including the referenced service information, the FAA has determined that AD action should be taken to prevent interference between the flap pushrod and the aileron pushrod caused by the flap actuator overtravel nut disengaging, which could result in loss of aileron control.

Explanation of the Provisions of This AD Since an unsafe condition has been identified that is likely to exist or develop in other Air Tractor AT-300, AT-400, and AT-500 series airplanes of the same type design, this AD requires installing both a new flap actuator overtravel stop and a roll pin through the overtravel stop and jack screw. Accomplishment of these installations is required in accordance with Snow Engineering Co. SL #140, dated November 27, 1995, Revised October 10, 1996. Since a situation exists (possible loss of aileron control) that requires the immediate adoption of this regulation, it is found that notice and opportunity for public prior comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited Although this action is in the form of a final rule that involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 96-CE-55-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a significant regulatory action under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies andProcedures, a final regulatory evaluation will be prepared and placed in the Rules Docket (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.

List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701.

Section 39.13 - [AMENDED] 2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: